I honestly have no idea. I think I remember reading that Arc may also be pinned to a somewhat old version of Racket / PLT Scheme. I could be misremembering thou

I honestly have no idea. I think I remember reading that Arc may also be pinned to a somewhat old version of Racket / PLT Scheme. I could be misremembering though. Depending on how portable Arc is to new versions of Racket, I'd guess they could move to a new Chez-backeneded Racket without any need to port.